1. Field of the Invention
The present invention relates to a resolver which detects an angular position of an object, and a manufacturing method of the resolver.
2. Description of the Related Art
Conventionally, a hydraulic power steering apparatus is used in a vehicle such as a passenger car or the like to assist an operator in maneuvering the vehicle. The hydraulic power steering apparatus uses a pump operated by an engine of the vehicle to generate force to assist the operator's steering. In recent years, an electric power steering (EPS) which uses a motor operated by a vehicle battery has become available. The EPS is more power efficient than the conventional hydraulic power steering.
In order to achieve highly accurate performance, the EPS requires an angle detection mechanism which is operable to accurately detect a rotary angle of the motor. Further, components used in the vehicle are required to function in various types of environments for a long period of time, and therefore, high reliability is expected of the angle detection mechanism of the EPS, which is one of the components used in the vehicle.
Therefore, a resolver of a variable reluctance type having an environmental resistance higher than an optical encoder or a magnetic encoder is often used as the angle detection mechanism for the EPS. In such a resolver, an exciting coil and an output coil (collectively “coils”) of a stator portion are formed by winding a wire around a plurality of teeth by using a winding apparatus, wherein an end portion of the wire is connected to a terminal pin arranged above a terminal block by welding or the like.
The conventional method of connecting the wire to the terminal pin, however, has a problem in that the connection between the wire and the terminal pin may be damaged by shocks and vibrations applied thereto from the vehicle due to a small radius of the wire used to form the coils. Further, when the wire which is wound around the terminal pin becomes unwound before the wire is welded to the terminal pin, the connection between the wire and the terminal pin is easily damaged due to the shocks and vibrations of the vehicle applied thereto.
Further, since the connection between the wire and the terminal pin is usually executed by a method such as welding which involves heat applied to the wire and the terminal pin, a terminal block which retains the terminal pin and which is made of a resin material may be deformed by the heat during the welding. Such deformation may cause the wire extending from the terminal pin to the coil to be erroneously connected to the terminal block causing the wire to be damaged by the shocks and vibrations of the vehicle.